Here is a fitness bag designed to take your pool exercises to the next level. The AquaBLAST is a water-filled kickboxing bag that floats below the water surface for your kicks, lifts, punches, and throws. It is ideal to use in pools from 3.5 to 5ft deep.
When filled, the AquaBLAST feels like a heavy bag but has outer walls that are flexible for low impact workouts. You can find out more about it here.